Graham Green once described a character of his as having "an air of unstable hilarity," a delightful phrase that I didn't fully appreciate until the incident in the cocktail lounge.

I was working, or rather posing, as a cocktail waitress at one of the larger Washington hotels whose name I dare not disclose. Why I was posing as a waitress is another story; but the truth is that I had no business mixing drinks -- or even serving them. As a teetotaler and one, moreover, who had never waited on tables before, I was singularly lacking in credentials.

One day, about a week after I'd begun work, the hotel simultaneously decanted three separate conventions into the cocktail lounge. In the strum und drang of the happy hour, the one island of tranquillity was the pianist riffling the keys and breathing lasciviously into the microphone. She was singing "Send in the Clowns" when the trouble began.

I was delivering an order of one bloody mary, two Heineken drafts and one vodka tonic to a table of pinstriped conventioneers. I had been clutching the tray in both hands, as was my amateurish wont, and in order to set the drinks down on the table with my right hand, I was naturally obliged to shift the tray over to my left.

So intent was I on this tricky maneuver that as I bent over to set the first Heineken down on the table, I absent-mindedly leaned across the bloody mary.

The man on my left leaped out of his chair and broke into a sort of barn dance, swatting at the bloody mary stains down the front of his suit. It was an awkward moment, made worse by the nervous giggles of the man sitting under my right elbow. But in the next moment, he had stopped giggling and was on his feet aping his associate. In trying to set things right I apparently had knocked the secont Heineken from my tray.

"That's great!" snapped the man who once had laughed so lightheartedly. Speechless and angry, the two victims wiped off their seats and sat down.

"I'm terribly sorry sir," I said to the gentleman on my right (the Heineken recipient), and leaned over -- I'm not sure why. Thus did I knock over the other beer -- his second, so to speak, of the evening.

The silence that followed was broken only by a voice from an adjoining table exclaiming, in genuine wonderment at my performance, "Jesus!" -- and by the cruelty of the crooning pianist as she reiterated her appeal to send in the clowns.

That was what set it off. I felt my face breaking into a grin best described by a participial phrase I must -- in the interests of decorum -- forego. Next I was chortling; then, seeing the the faces of the men who were suffering insult on top of injury, I was shaking with laughter.

I don't know how long I stood there, but at last some concerned citizen mercifully reached over and gave me a push, saying "Go!" I went, stumbling into the kitchen.

A waitress would glance over in my direction while hurriedly scooping ice into a glass and ask, "What's the matter?" But then she'd rush off without waiting for my answer, which I was incapable of completing in any case. I could never get beyond the "I spilled . . . "

At last, wiping away my tears, I confessed my crime to the unflappable beverage manager. He made a strangled noise and for a moment I thought he was going to bash me across the ear, but he was only reaching across the bar to fill a bucket with soda water.

"Bring this and come with me," he ordered. I suffered the further humiliation, upon reaching the table, of seeing four grown men shrink back from me.

The beverage manager inclined his long elegant frame over the table to whisper who knows what words of apology and comfort. He rubbed his hands together in the inimitable maitre d'hotel manner. Finally he began dipping wads of paper napkins into the soda water and applying them to the stained suits with infinite buy ineffectual care.

When I returned to the kitchen, my faculties had been impaired by the crippling seizure of mirth; as I added up the check for that unfortunate table, I suddenly suffered a blackout -- I couldn't for the life of me figure the 4 percent tax.

In desperation, I enlisted the bartender's help, a move I soon regretted. A normally ill-tempered man, he had been pushed to the limits of his endurance by the day's crises, to which I had contributed amply.

"You don't understand?" he shouted. "How come you don't understand? How come you so stupid?" (They sometimes talk that way in Thailand, whence he hailed.)

At that I became unhinged once more, desperately unhappy but convulsed with laughter. By now the bartender was braying at me, and all I could do was stare into the gaping depths of his jaw as he repeated, "How come you so stupid?" -- and howl. Meanwhile, my beer and bloody mary-soaked customers walked out on their bill, for which I could scarcely blame them.

I quit the job before the hotel could fire me. It was a question of face. People have been canned for drinking on the job or sleeping on the job. But to be dismissed for laughing on the job seemed to me an indignity too shameful to comtemplate.

And so I left in the Shakespearian tradition: exit laughing.